The invention relates to an electronic chess clock with a generally rectangular casing containing two clockworks each with a clock face and a set of hands. An adjusting device is provided for each of the clockworks at the rear of the casing to set the hands, and a change-over device is located at the top of the casing by which one or both of the clockworks can be stopped.
Such chess clocks have been known generally for some time, and are commercially available. The clocks use spring operated clockworks with a balance which can be stopped by means of a mechanical brake actuated from the top of the casing. The brake for each clockwork is attached to a type of switching lever. Both clockworks can be stopped when the switching lever is in an intermediate position, for example, when both clocks must be stopped during a game interruption.
After relatively short use of about half a year, the known mechanical chess clocks develop a relatively high inaccuracy in operation. In addition, some models can easily be "manipulated". One example of such manipulation can be the setting ahead by one player of the rate controller of his opponent's clockwork, while setting back the rate controller of his own clockwork. Another possibility for manipulation arises through the construction of the brake, wherein a sudden actuation of the switch on the top of the casing causes the balance to accelerate strongly and thus shorten the opponent's time.
Today, two types of chess clocks are in use for tournaments. One type is used during standard matches wherein, except for the brake, the clockwork corresponds completely in design and construction to a conventional clockwork. The other type is used during very short matches and resembles a type of short time meter for a maximum match time of 15 minutes.
All chess clocks have in common the fact that they provide an analogous representation of game time with two separate, alternately running and stopping indicators, and the clock faces and change-over devices are arranged in such a way that their positions are visible from a great distance. Also, the clocks lack acoustical or optical signal devices with the exception of a drop leaf which is actuated by the minute hand.
A chess clock is known from German Utility Model No. 78 20 464, in which quartz-controlled electronic timework controls a digital indicator which is equipped with a liquid crystal display. However, this electronic chess clock was not accepted for tournament use, because it did not meet the regulations of the chess club nor the requirements of the chess players involved.